1. Field of the Invention
The present invention relates to a method and apparatus for refilling an ink cartridge and more particularly to a method, apparatus and a kit for refilling an ink-jet cartridge that has therein a spring for maintaining negative pressure on the ink in the ink cartridge.
2. Prior Art
In order to protect the environment and save energy, it is today's common practice to reuse used printer ink cartridges and not just discard them. In other words, when an ink cartridge (merely called "cartridge") designed for use in computer printers, particularly in ink-jet printers, runs out of ink, the cartridge is refilled with ink so that the thus refilled cartridge can be installed back in the printers for further use.
There are many different types of cartridges that are currently manufactured and marketed. One type of cartridge includes a spring means installed inside the ink reservoir provided in the cartridge.
More specifically, as shown in FIG. 9 which shows an interior of a typical ink cartridge that has therein a spring means, the cartridge 100 is comprised of a main casing 102 and two side coverings 102a and 102b that fit on the main casing 102 to form a hollow enclosure, and an ink reservoir 110 is installed therein. The cartridge 100 further has a head part 100' and other elements (those elements, however, will not be described since they are not particularly relevant to the present invention). The ink reservoir 110 comprises a flexible reservoir bag 110' which is made of, for instance, plastic or foil, two opposed side plates 112a and 112b installed in the reservoir bag 110', and a spring means 114 provided between the side plates 112a and 112b. The spring means 114 is in substantially an oval shape obtained by a pair of metal sheets 114a and 114b which are respectively adhered to the side plates 112a and 112b. When a pressing force is applied in a direction of arrow P so as to push the pair of the metal sheets 114a and 114b towards each other, the spring means 114 is compressed and changes its shape as shown by a dotted line; and when such a compression force is released, the spring means 114 is brought back to its original shape as shown by a solid line.
FIG. 10 shows an exterior of the cartridge 100. The cartridge 100 has a head part 100' and an ink filling aperture 120 that communicates with the ink reservoir 110. The ink filling aperture 120 is closed by a metal ball 122 which is covered by a closing seal 124. In addition, interior access slits or openings 130 are formed between the main casing 102 and the side coverings 102a and 102b. These interior access slits or openings 130 are used so that both ends of an ink amount indicating tape (not shown) are inserted thereinto. The interior access slits 130 and the ink amount indicating tape are covered by a covering seal 140.
In this cartridge 100, the spring means 114 is provided so as to generate and keep a negative pressure on the ink stored in the ink reservoir 110. More specifically, the ink stored inside the ink reservoir 110 generates pressure that is applied to not only the ink reservoir 110 but also the head part 100' of the cartridge through which the ink is supplied from the cartridge 100 to a printer. Thus, the ink tends to flow out of the cartridge 100 through the head part 100' by its own pressure. The spring means 114 prevents such a flow out of the ink. In other words, the spring means 114 produces an expanding force in the direction in which the metal sheets 114a and 114b are set apart from each other along the smaller diameter of the oval shape (or in the direction opposite from the arrow P in FIG. 9), and this expanding force generates a negative pressure inside the ink reservoir 110 which is smaller than the atmospheric pressure. As a result, the ink inside the ink reservoir 110 is prevented from leaking out through the head part 100' of the cartridge 100 since it is kept under the negative pressure.
Generally, currently marketed ink refilling devices are used such that: the ink filling aperture of the cartridge, which was used for initially filling the ink in the cartridge and sealed with a metal ball, is first opened by removing the metal ball; the refilling device is coupled to the thus opened ink filling aperture; and then, an ink tube is set in and coupled to the refilling device, thus letting the ink in the ink tube flow into the ink reservoir of the cartridge forcibly or by way of gravity. Upon completion of this ink filling process, the refilling device is removed, the ink filling aperture is closed by a closing plug, and then the refilled cartridge is put back in the printer.
Accordingly, when such an ink refilling device is used for the cartridge that includes a spring means as described above and shown in FIGS. 9 and 10, the spring means 114, that has been in the shape shown by the dotted lines in FIG. 9 after the ink in the ink reservoir 110 was used up, expands until its further expansion is restrained by the inner surfaces of the side coverings 102a and 102b of the cartridge 100 by way of the exterior air comes into the ink reservoir 110 upon the removal of the metal ball 122 from the ink filling aperture 120; and after the completion of the ink refill process, there is no way to bring the spring means 114 to be compressed and then let it expand to produce a negative pressure inside the ink reservoir 110. As a result, the refilled ink leaks out through the head part 100' of the cartridge 100, occasionally damaging the print head of the printer.
In short, the existing ink refilling device cannot provide an ink cartridge with a negative pressure inside the ink reservoir.